Facile-Effective Hole-Transporting Materials Based on Dibenzo[a,c]carbazole: The Key Role of Linkage Position to Photovoltaic Performance of Perovskite Solar Cells

The film morphology of the hole-transporting layer is proved to be the key element to charge transfer and the interfacial property in perovskite solar cells. In this Letter, a new dibenzo[a,c]carbazole (DBC) core with multiple reaction sites has been formed with a Y-shape, in which the phenanthrene group was integrated as a plane π structure into the common carbazole moiety. Accordingly, three DBC-based hole-transporting materials (HTMs) with varied molecular configurations were synthesized by the introduction of N-(4-methoxyphenyl)-9,9-dimethyl-9H-fluoren-2-amine (F(Me)NPh) as the periphery group at different linkage positions. Once applied to perovskite solar cells as HTMs, DBC-2 with the twisted and asymmetric structure achieved the highest conversion efficiency of 20.02%. Also, the corresponding dopant-free device exhibited a PCE of 16.43% and good device stability under glovebox and ambient conditions.